Fix wrong page count returned in FPDF_GetPageCount() during loading dynamic XFA files

fpdfsdk/src/fpdfview.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "public/fpdfview.h"
 
 #include "../include/fpdfxfa/fpdfxfa_app.h"
 #include "../include/fpdfxfa/fpdfxfa_doc.h"
@@ skipping 398 matching lines @@
 DLLEXPORT int STDCALL FPDF_GetSecurityHandlerRevision(FPDF_DOCUMENT document) {
   CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
   if (!pDoc)
     return -1;
 
   CPDF_Dictionary* pDict = pDoc->GetParser()->GetEncryptDict();
   return pDict ? pDict->GetInteger("R") : -1;
 }
 
 DLLEXPORT int STDCALL FPDF_GetPageCount(FPDF_DOCUMENT document) {
-  CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
+  CPDFXFA_Document* pDoc = static_cast<CPDFXFA_Document*>(document);
   return pDoc ? pDoc->GetPageCount() : 0;
 }
 
 DLLEXPORT FPDF_PAGE STDCALL FPDF_LoadPage(FPDF_DOCUMENT document,
                                           int page_index) {
   if (!document)
     return nullptr;
   CPDFXFA_Document* pDoc = static_cast<CPDFXFA_Document*>(document);
   if (page_index < 0 || page_index >= pDoc->GetPageCount())
     return nullptr;
@@ skipping 627 matching lines @@
   if (!buffer) {
     *buflen = len;
   } else if (*buflen >= len) {
     memcpy(buffer, utf16Name.c_str(), len);
     *buflen = len;
   } else {
     *buflen = -1;
   }
   return (FPDF_DEST)pDestObj;
 }